1. Field of the Invention
The present invention relates to a projector having a light source and a projection optical system for enlarging and projecting a light beam irradiated by the light source after being modulated in accordance with image information, in which an optical path from the light source to the projection optical system is approximately arranged in planarly-viewed L-shape.
2. Description of Related Art
Conventionally, a projector has been used for presentation at a conference, scientific society and exhibition. Such projector forms an optical image by modulating a light beam irradiated by a light source with an optical modulator in accordance with image information to enlarge and project the optical image.
In order to vividly display the projected optical image, luminance of the light source has to be improved, which accompanies heat generated on the light source. In order to efficiently cool the light source and prevent the heat from remaining inside the projector, a suction fan is ordinarily used.
In a projector having an optical path of planarly-viewed L-shape from the light source to the optical modulator, the suction fan is provided adjacent to both of the light source and an exterior case for absorbing the heat generated on the light source and discharge the heated air from an exhaust hole formed on a rear side (opposite side from the projecting direction of the projector) or lateral side of the exterior case.
However, since the suction fan is located adjacent to the exterior case, wind noise is caused by the suction fan when the heated air is discharged from the exhaust hole. Further, the noise of the suction fan itself is more easily transferred to the outside, so that noise is likely to be caused while using the projector.
Further, since the exhaust hole is formed on the rear side or the lateral side of the exterior case, the heated air discharged from the projector is directly blown to the spectators viewing the projected image at the rear or the lateral side of the projector, thereby causing unpleasant feeling to the spectators.
An object of the present invention is to provide a projector capable of improving cooling efficiency of a light source, securing sufficient silentness and causing no unpleasant feeling to the spectators.
A projector according to an aspect of the present invention has: a light source; a projection optical system that enlarges and projects a light beam irradiated by the light source after being modulated in accordance with image information, where an optical path from the light source to the projection optical system is arranged approximately in planarly-viewed L-shape; and a light source cooling axial-flow fan provided adjacent to the light source with a suction surface thereof extending along the optical axis of the light beam irradiated by the light source, the exhaust direction of the light source cooling axial-flow fan being parallel to the projecting direction of the projection optical system.
According to the present invention, in a projector having a light path shaped in approximately planarly-viewed L-shape from a light source to a projection optical system, since the light source cooling axial-flow fan is adjacent to the light source and the suction surface extends along the optical axis of the light irradiated by the light source, the exhaust direction of the light source cooling axial-flow fan being parallel to the projecting direction of the projection optical system, an exhaust hole of the cooling air formed on the exterior case can be spaced apart from the light source cooling axial-flow fan, so that the wind noise caused by the cooling air blown from the light source cooling axial-flow fan and the sound of the light source cooling axial-flow fan itself can be diminished, thereby securing the silentness while using the projector.
Since the exhaust hole formed on the exterior case is located on a projection side of the projector, the heat wind discharged from the projector is exhausted from the projection side, thereby preventing the heat wind from being blown onto a viewer located on the backside or a lateral side of the projector.
Since the light source cooling axial-flow fan is adjacent to the light source, the air heated by the light source can be efficiently inhaled, thereby avoiding rise in temperature of a light source so that the heat can be prevented from residing inside the projector.
Accordingly, the cooling efficiency of the light source can be sufficiently improved while securing the silentness of the projector and causing no unpleasant feeling on the spectators.
The projector of the present invention may preferably have an exterior case that accommodates the light source and the projection optical system, the exterior case having an exhaust hole that discharges an air inside the exterior case toward outside and a duct that connects a discharge portion of the light source cooling axial-flow fan with the exhaust hole of the exterior case.
According to the above arrangement, since the discharge portion of the light source cooling axial-flow fan and the exhaust hole of the exterior case are connected by the duct, the air discharged by the light source cooling axial-flow fan is discharged from the exhaust hole through the inside of the duct, the exhaust flow can be prevented from colliding with the components of the projector and the inside temperature can be prevented from being raised by avoiding backflow of the exhaust toward the inside of the product, so that the rise in the inside temperature can be prevented and the wind noise can be restrained, thereby improving silentness of the projector.
In the projector according to the present invention, the light source and the projection optical system may preferably be accommodated in an optical component casing approximately of planarly-viewed L-shape, a lamp driving circuit block that drives the light source and/or a power source block for supplying electric power to the lamp driving circuit block may preferably be disposed in a space surrounded by the duct and the casing, and a block cooling axial-flow fan that cools the lamp driving circuit block and/or the power source block may preferably disposed on a side of the projection optical system, the air-flow rate of the block cooling axial-flow fan being smaller than the air-flow rate of the light source cooling axial-flow fan.
According to the above arrangement, since the light source and the projection optical system are accommodated in the optical components casing of approximately planarly-viewed L-shape and the lamp driving circuit block and/or the power source block are disposed in the space surrounded by the duct and the casing, the space inside the projector can be efficiently utilized and the components inside the projector can be highly densely installed, thereby reducing the size of the projector.
In an ordinary arrangement, a projector has a control board installed with a CPU etc. for importing image information to control and operation processing in order to project an optical image in accordance with the image information, and the power source block supplies great electric current with low voltage to the CPU installed on the control board, heat is easily generated.
Further, the lamp driving circuit block has heating elements such as a transforming coil for transforming the electric power from the power source into a predetermined level of power, a capacitor for storing the electric power, and a resistor.
Since the block cooling axial-flow fan is located on a side of the projection optical system, the above-described heat-generating power source block or the lamp driving circuit block can be efficiently cooled, thereby preventing deterioration of the power source block or the lamp driving circuit block.
Further, since the air-flow rate of the block cooling axial-flow fan is smaller than the air-flow rate of the light source cooling axial-flow fan, the heat wind blown from the block cooling axial-flow fan is efficiently inhaled by the light source cooling axial-flow fan and discharged toward the outside of the projector, and the wind noise caused when the heat wind blown by the block cooling axial-flow fan collides with the components of the projector, thereby reducing the noise while using the projector can be reduced.
In the projector according to the present invention, the block cooling axial-flow fan may preferably be covered with a duct for guiding a cooling air toward the lamp driving circuit block and/or the power source block.
According to the above arrangement, since the block cooling axial-flow fan is covered with a duct for guiding the cooling air to the lamp driving circuit block and/or the power source block, the cooling air inhaled and discharged by the block cooling axial-flow fan is securely introduced to the lamp driving circuit block and/or the power source block through the inside of the duct, thereby improving the cooling efficiency of the lamp driving circuit block and/or the power source block.